ACCELERATION SENSOR

• US 20100300204A1
• Filed: 05/19/2010
• Published: 12/02/2010
• Est. Priority Date: 05/26/2009
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: REINMUTH, Jochen
• Granted Patent: US 8,347,721 B2
• Time in Patent Office: Days
• US Class Current: 73/514.32
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 2015/0831 the mass being of the paddle type having the pivot axis between the longitudinal ends of the mass, e.g. see-saw configuration

Abstract

A micromechanical acceleration sensor includes a substrate with a substrate surface arranged in one plane, a first counter-electrode arranged on the substrate surface, a second counter-electrode arranged on the substrate surface, and a rocking mass arranged above the first counter-electrode and the second counter-electrode. The rocking mass is in this case connected to the substrate via a torsion spring which permits tilting of the rocking mass about an axis of rotation. Further provided are a first compensation counter-electrode arranged on the substrate surface and a second compensation counter-electrode arranged on the substrate surface. In addition, a first compensation electrode is arranged above the first compensation counter-electrode and a second compensation electrode is arranged above the second compensation counter-electrode.

Claims

1. A micromechanical acceleration sensor, comprising:

a substrate having a substrate surface arranged in one plane;

a first counter-electrode arranged on the substrate surface;

a second counter-electrode arranged on the substrate surface;

a rocking mass arranged above the first counter-electrode and the second counter-electrode, wherein he rocking mass is connected to the substrate via a torsion spring, the torsion spring permitting tilting of the rocking mass about an axis of rotation;

a first compensation counter-electrode arranged on the substrate surface and a second compensation counter-electrode arranged on the substrate surface;

a first compensation electrode arranged above the first compensation counter-electrode; and

a second compensation electrode arranged above the second compensation counter-electrode.

2. The micromechanical acceleration sensor of claim 1, wherein the first compensation electrode and the second compensation electrode are rigidly connected to the substrate.

3. The micromechanical acceleration sensor of claim 1, wherein the first counter-electrode is electrically connected to the second compensation counter-electrode, and the second counter-electrode is electrically connected to the first compensation counter-electrode.

4. The micromechanical acceleration sensor of claim 1, wherein the first compensation electrode and the second compensation electrode are configured symmetrically to each other in terms of a mirroring at the torsion spring.

5. The micromechanical acceleration sensor of claim 1, wherein the first compensation counter-electrode and the second compensation counter-electrode are configured symmetrically to each in terms of a mirroring at the torsion spring.

6. The micromechanical acceleration sensor of claim 1, wherein without an acceleration acting on the acceleration sensor, a first electrical sensor capacitance between the rocking mass and the first counter-electrode is of approximately the same magnitude as a first electrical compensation capacitance between the second compensation electrode and the second compensation counter-electrode, and wherein a second electrical sensor capacitance between the rocking mass and the second counter-electrode is of approximately the same magnitude as a second electrical compensation capacitance between the first compensation electrode and the first compensation counter-electrode.

7. The micromechanical acceleration sensor of claim 6, wherein the acceleration sensor is connectable to an evaluation circuit which is configured to calculate a difference between a sum of the first electrical sensor capacitance and the first electrical compensation capacitance and a sum of the second electrical sensor capacitance and the second electrical compensation capacitance.

8. The micromechanical acceleration sensor of claim 1, wherein the first compensation electrode is connected to the substrate via a first post at an end of the first compensation electrode toward the torsion spring, and the second compensation electrode is connected to the substrate via a second post at an end of the second compensation electrode toward the torsion spring.

9. The micromechanical acceleration sensor of claim 1, wherein the torsion spring, the first compensation electrode and the second compensation electrode are connected to the substrate at a common suspension post.

10. The micromechanical acceleration sensor of claim 1, wherein the rocking mass partially surrounds the first compensation electrode.

11. The micromechanical acceleration sensor of claim 1, further comprising:

at least one of a plurality of first counter-electrodes and a plurality of first compensation counter-electrodes.

12. A method for operating a micromechanical acceleration sensor, the method comprising:

acquiring a first sum of a first electrical sensor capacitance and a first electrical compensation capacitance;

acquiring a second sum of a second electrical sensor capacitance and a second electrical compensation capacitance;

calculating a difference between the first sum and the second sum;

determining a magnitude and a direction of an acceleration acting on the acceleration sensor based on the amount and sign of the difference;

wherein the micromechanical acceleration sensor, includes;

a substrate having a substrate surface arranged in one plane;

a first counter-electrode arranged on the substrate surface;

a second counter-electrode arranged on the substrate surface;

a rocking mass arranged above the first counter-electrode and the second counter-electrode, wherein he rocking mass is connected to the substrate via a torsion spring, the torsion spring permitting tilting of the rocking mass about an axis of rotation;

a first compensation counter-electrode arranged on the substrate surface;

a second compensation counter-electrode arranged on the substrate surface;

a first compensation electrode arranged above the first compensation counter-electrode; and

a second compensation electrode arranged above the second compensation counter-electrode.